Wastewater treatment( general introduction )
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In this presentation general introduction about sewage water, which is collected form domestic houses.
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Wastewater treatment( general introduction )
- 2. ANUDEEP NEMA Ph.D , SVNIT Surat
- 3. ο Usually refer to sewage treatment, or domestic wastewater treatment ο process of removing contaminants from wastewater, both runoff and domestic
- 4. ο To produce waste stream (effluent) ο To produce solid waste (sludge) ο To discharge or reuse them back into the environment
- 5. ο Residences (kitchen, bathroom) ο Commercial institution ο Industrial institution (usually require specialized treatment process)
- 6. ο collected and transported via a network of pipes and pump stations to a municipal treatment plant
- 7. ο Primary ο solids are separated ο Secondary ο dissolved biological matter is converted into a solid mass by using water-borne bacteria ο 95% of the suspended molecules should be removed ο Tertiary ο biological solids are neutralized then disposed, and treated water may be disinfected chemically or physically
- 8. ο Mechanical treatment ο Influx (Influent) ο Removal of large objects ο Removal of sand and grit ο Primary Sedimentation ο Biological treatment ο Trickling bed filter ο Activated sludge ο Chemical treatment ο Disinfection
- 9. ο Remove large objects ο Ex: sticks, rags, toilet paper, tampons ο Raked screen ο Clog equipment in sewage treatment plant
- 10. ο typical materials that are removed during primary treatment include ο fats, oils, and greases (aka FOG) ο sand, gravels and rocks (aka grit) ο larger settleable solids including human waste, and ο floating materials
- 11. ο Sand catcher ο Remove sand and grit ο Control wastewater velocity ο Sand grit and stone settle ο Keep suspended organic matter in water ο Damage equipments in the remaining treatment stage ο Landfill
- 12. ο Primary Sedimentation Tank ο Remove grease, oil ο Fecal solid settle, floating material rise to the surface ο Produce a homologous liquid for later biological treatment ο Fecal sludge are pumped to sludge treatment plant
- 13. ο Degrade biological content (dissolved organic matter) of the sewage ο Ex: human waste, food waste, soaps, detergent ο Added bacteria and protozoa into sewage ο 3 different approaches ο Fixed film system ο Suspended film system ο Lagoon system
- 14. ο Fixed Film Systems ο grow microorganisms on substrates such as rocks, sand or plastic ο wastewater is spread over the substrate ο Ex: Trickling filters, rotating biological contactors
- 15. ο Spread wastewater over microorganism ο made of coke (carbonised coal), limestone chips or specially fabricated plastic media ο Optimize their thickness by insect or worm grazing
- 16. ο Suspended Film Systems ο stir and suspend microorganisms in wastewater ο settled out as a sludge ο pumped back into the incoming wastewater ο Ex: Activated sludge, extended aeration
- 17. ο mixed community of microorganisms ο Both aerobic and anaerobic bacteria may exist ο Biological floc is formed
- 18. ο aeration tank ο oxygen is introduced into the system
- 19. ο aeration source ο ensure that adequate oxygen is fed into the tank ο provided pure oxygen or compressed air
- 20. ο secondary clarifiers ο activated-sludge solids separate from the surrounding wastewater
- 21. ο Activated sludge outflow line ο Pump activated sludge back to the aeration tank ο Effluent outflow line ο discharged effluent into bay or tertiary treatment plant
- 23. ο Lagoon Systems ο hold the waste-water for several months ο natural degradation of sewage ο Usually reeds are preferred
- 24. ο remove disease-causing organisms from wastewater ο 3 different disinfection process ο Chlorination ο UV light radiation ο Ozonation
- 25. ο Most common ο Advantages: low cost & effective ο Disadvantages: chlorine residue could be harmful to environment
- 26. ο Damage the genetic structure of bacteria, viruses and other pathogens. ο Advantages: no chemicals are used ο water taste more natural ο Disadvantages: high maintenance of the UV- lamp
- 27. ο Oxidized most pathogenic microorganisms ο Advantages: safer than chlorination fewer disinfection by-product ο Disadvantage: high cost
- 28. ο discharged into a stream, river, bay, lagoon or wetland ο used for the irrigation of a golf course, green way or park ο If itβs sufficiently clean, it can be used for groundwater recharge
- 29. ο Nitrogen removal ο Ammonia (NH3) β nitrite (NO2 - )β nitrate (NO3 - ) ο Phosphorous removal ο Precipitation with iron or aluminums salt ο Lead to eutrophication ο May cause algae bloom
- 30. ο Primary sludge usually have strong odors ο Secondary sludge have high concentration of microorganism ο Goals of treatments are: ο Reduce odors ο Remove water reduce volume ο Decompose organic matter
- 31. ο Untreated sludge are about 97 percent water ο Settling can reduce about 92 to 96 percent of water ο dried sludge is called a sludge cake
- 32. ο Aerobic digestion ο Anaerobic digestion ο composting
- 33. ο Bacterial process ο Need oxygen ο Consume organic matter ο Convert into carbon dioxide (CO2)
- 34. ο Bacterial process ο Do not require oxygen ο Consume organic matter ο Produce biogas, which can be used in generators for electricity
- 35. ο aerobic process ο requires the correct mix of carbon, nitrogen, oxygen and water with sludge ο Generate large amount of heat
- 36. ο Superheat sludge and convert into small granules that are rich in nitrogen ο Sell it to local farmer as fertilizer ο Spread sludge cake on the field ο Save landfill space